Power Injector with Decay Constant Functionality

ABSTRACT

A power injector ( 154 ) is disclosed that may utilize decay constant determination logic ( 192 ). This logic ( 192 ) in turn may incorporate a test injection protocol ( 194 ). The test injection protocol ( 194 ) may be executed to acquire data for the derivation of a flow rate decay constant. The derived flow rate decay constant may be used by the power injector ( 154 ) to execute of an injection protocol ( 162 ), for instance in conjunction with an operation of an imaging unit ( 152 ) for an imaging operation.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/090,911 filed on 22 Aug. 2008 entitled “POWER INJECTOR WITH DECAYCONSTANT FUNCTIONALITY”.

FIELD OF THE INVENTION

The present invention generally relates to the field of power injectorsand, more particularly, to a power injector configured to provide aninjection on an exponentially decaying flow rate basis.

BACKGROUND

Various medical procedures require that one or more medical fluids beinjected into the patient. Medical imaging procedures oftentimes involvethe injection of a contrast media into the patient, possibly along withsaline or other fluids. Other medical procedures involve injecting oneor more fluids into a patient for therapeutic purposes. Power injectorsmay be used for these types of applications.

A power injector generally includes what is commonly referred to as apowerhead. One or more syringes may be mounted to the powerhead invarious manners (e.g., detachably; rear-loading; front-loading;side-loading). Each syringe typically includes what may be characterizedas a syringe plunger, piston, or the like. Each such syringe plunger isdesigned to interface with (e.g., contact and/or temporarilyinterconnect with) an appropriate syringe driver that is incorporatedinto the powerhead, such that operation of the syringe driver axiallyadvances the associated syringe plunger inside and relative to a barrelof the syringe. One typical syringe driver is in the form of a ram thatis mounted on a threaded lead or drive screw. Rotation of the drivescrew in one rotational direction advances the associated ram in oneaxial direction, while rotation of the drive screw in the oppositerotational direction advances the associated ram in the opposite axialdirection.

Contrast media may be injected by a power injector into a patient'sheart for an imaging operation, such as for a computed tomographyangiogram. In an attempt to have the enhancement levels of the right andleft sides of the patient's heart be more uniform, where thisenhancement is provided by a contrast media injection, power injectorshave been configured to use an injection protocol that in turn utilizesa flow rate decay constant. Such a flow rate decay constant provides anexponentially decaying flow rate injection.

SUMMARY

First and second aspects of the present invention are each embodied by apower injector, which includes a syringe plunger driver, a syringe,power injector control logic, and data storage. The syringe plungerdriver includes a motorized drive source. The syringe includes a syringeplunger, where the syringe plunger driver interacts with the syringeplunger to move the same in at least one direction. The power injectorcontrol logic includes an injection protocol, which in turn utilizes aflow rate decay constant. The data storage is accessible by the powerinjector control logic. In the case of the first aspect, the datastorage includes a plurality of data entries, where each data entryincludes a flow rate decay constant value. In the case of the secondaspect of the present invention, each data entry includes an imagingdevice identifier and an associated flow rate decay constant value.

A number of feature refinements and additional features are separatelyapplicable to each of the first and second aspects of the presentinvention. These feature refinements and additional features may be usedindividually or in any combination. The following discussion isseparately applicable to each of the first and second aspects, up to thestart of the discussion of a third aspect of the present invention. Thepower injector may include a display or graphical user interface. Afirst output may be presented on this display or graphical userinterface, where this first output is in the form of a listing of atleast some of the data entries. In one embodiment, this first outputpresents a model or a model identifier for an imaging unit (e.g., a CTscanner), along with an associated flow rate decay constant value (e.g.,in the form of a drop down menu).

The power injector may be configured such that the noted data storage issearchable in any appropriate manner. In one embodiment, a user isallowed to enter information regarding an imaging unit that is to beused in combination with the power injector for an imaging operation,and the noted data storage may be searched to attempt to identify suchan imaging unit and its corresponding flow rate decay constant.Regardless of how information is obtained on a flow rate decay constantvalue for an associated imaging unit, the power injector may beconfigured to allow this flow rate decay constant value to be input inany appropriate manner, such as by any appropriate data input deviceoperatively interconnected with the power injector control logic (e.g.,a keyboard, a mouse, a touch screen display, a soft key display, a touchpad, a track ball, or the like).

A third aspect of the present invention is embodied by a power injector.This power injector includes a syringe plunger driver, a syringe, andpower injector control logic. The syringe plunger driver includes amotorized drive source. The syringe includes a syringe plunger, wherethe syringe plunger driver interacts with the syringe plunger to movethe same at least one direction. The power injector control logicincludes an injection protocol, which in turn utilizes a flow rate decayconstant. The power injector control logic further includes decayconstant determination logic.

A number of feature refinements and additional features are applicableto the third aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to the third aspect, up to thestart of the discussion of a fourth aspect of the present invention. Inone embodiment, the decay constant determination logic includes a testinjection protocol. Execution of this test injection protocol may beused to acquire information such that a value may be derived for a flowrate decay constant to be used in a subsequent imaging operationinvolving the power injector.

The decay constant determination logic may utilize an acquisition timevariable. A prompt may be utilized for inputting a value for thisacquisition time variable. In one embodiment, an average value is inputfor the acquisition time variable (e.g. based upon a priori knowledgefrom operation of an imaging unit to be used in combination with thepower injector to acquire a patient image). In one embodiment, apatient-specific value is input for the acquisition time variable (e.g.,dividing the number of patient heartbeats required for an imaging unit(to be used in combination with the power injector) to acquire a patientimage, divided by the number of patient heartbeats per unit of time).

The decay constant determination logic may utilize an enhancement levelvariable. A prompt may be utilized for inputting a value for thisenhancement level variable. The value for the enhancement level variablemay be selected/determined by an operator of an imaging system that isutilizing the power injector. This value may be expressed as apercentage for the case where the patient image to be acquired is of aheart. In this regard, the value for the enhancement level variable maybe a desired enhancement level for the left side of the patient's heart,expressed as a percentage of the enhancement level on the right side ofthe patient's heart.

The decay constant determination logic may utilize a time delayvariable. A prompt may be utilized for inputting a value for this timedelay variable, and in any case a patient-specific value may be inputfor the time delay variable. In one embodiment, the value for the timedelay variable is the amount of time required from the start of aninjection (pursuant to the test injection protocol) until the inputvalue for the enhancement level variable is realized (e.g., until thedesired enhancement level is reached on the left side of the patient'sheart).

In one embodiment, the decay constant determination logic utilizes eachof the noted acquisition time, enhancement level, and time delayvariables. A decay constant value generated by the decay constantdetermination logic may be equal to the time delay variable, minusone-half of the acquisition time variable, divided into the naturallogarithm of the enhancement level variable.

A fourth aspect of the present invention is embodied by a method ofacquiring a medical image using an imaging system, where this imagingsystem includes a power injector and an imaging unit. A search may beconducted for a value to be used for a flow rate decay constant, wherethis search is based upon a model or model number of the imaging unit tobe used for the imaging operation. A value is input for the flow ratedecay constant, and that is associated with the model of the particularimaging unit to be used for the imaging operation. An injection is thendelivered by operation of the power injector using the inputted valuefor the flow rate decay constant.

A number of feature refinements and additional features are applicableto the fourth aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to the third aspect, up to thestart of the discussion of a fifth aspect of the present invention. Theinjection associated with the fourth aspect may facilitate acquisitionof a patient image (e.g., an image of a patient's heart). In oneembodiment, the imaging unit is operated during and/or after theinjection to acquire a patient image for flow rate constantdetermination purposes. Although the fourth aspect may be used for anyimaging application, in one embodiment the imaging operation is forpurposes of a computed tomography angiogram.

A prompt may be provided for entry of a value of the flow rate of decayconstant to be used for an injection provided by operation of the powerinjector. In one embodiment, this prompt is presented on a displayassociated with the power injector (e.g., a display on a powerhead ofthe power injector; on a remote console associated with the powerinjector). Any appropriate data entry vice may be utilized to input adesired value for the flow rate decay constant, including withoutlimitation a keyboard, a mouse, a touch screen display, a soft keydisplay, a touch pad, a track ball, or the like.

The search for a value for the flow rate decay constant may includeaccessing or consulting a cross-reference of imaging unit model numbersto flow rate decay constants. This cross-reference may be stored onand/or incorporated by power injector control logic utilized by thepower injector. However, this cross-reference could be in anyappropriate form (e.g., hard copy) and stored at any appropriatelocation.

Another option for the search regarding a value for the flow rate decayconstant may entail retrieving a value from memory associated with thepower injector. The search may entail accessing a lookup tableincorporated by the power injector. Yet another option would be to usethe Internet for the search. Any appropriate search may be undertaken toidentify a value for the flow rate decay constant to be used for anejection provided by the power injector for purposes of undertaking animaging operation.

A fifth aspect of the present invention is embodied by a method foracquiring a medical image using an imaging system, where this imagingsystem includes a power injector and an imaging unit. A first injectionis delivered to a patient. This first injection is monitored, and a flowrate decay constant is derived based at least in part from thismonitoring of the first injection. Thereafter, a second injection isdelivered to the patient and which uses the derived flow rate decayconstant.

A number of feature refinements and additional features are applicableto the fifth aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to at least this fifth aspect ofthe present invention. The first injection may utilize any appropriatefluid or combination of fluids (e.g., contrast media, alone or incombination with saline), may inject any appropriate fluid volume (e.g.,no more than at least generally about 15 mL in one embodiment; no morethan at least generally about 10 mL in one embodiment; within a rangefrom at least generally about 5 mL to at least generally about 15 mL(inclusive) in one embodiment), and may utilize any appropriate flowrate (e.g., a constant flow rate within a range of at least generallyabout 3-6 mL/second in one embodiment; a constant flow rate within arange of at least generally about 4-5 mL/second in one embodiment; aconstant flow rate of no more than at least generally about 6 mL/secondin one embodiment). As this first injection may be used at least in partto acquire a value for the flow rate decay constant, it may becharacterized as a test injection.

The monitoring of the first injection may be for purposes of acquiringdata to be used in the derivation of a value for the flow rate decayconstant. As the first injection may entail an injection of a fluid intothe patient, the monitoring of the first injection may be characterizedas acquiring this patient-specific data. The monitoring of the firstinjection may entail monitoring an image intensity of at least part ofthe heart of the patient.

In one embodiment, the fifth aspect is directed to executing a computedtomography angiogram. In this and for any other appropriate case, themonitoring for purposes of the first injection may entail monitoring animage intensity of the left side of the patient's heart as a result ofthe first injection. This monitoring may also include determining theamount of time required for the image intensity of the left side of thepatient's heart (from the first injection) to reach a predeterminedlevel (e.g., an input value for an enhancement level variable inaccordance with the above-noted third aspect), and which may beexpressed as a percentage of the intensity of the right side of thepatient's heart (from the first injection). The target enhancement levelmay be at least generally about 50% in one embodiment, and may be atleast generally about 25% in another embodiment (e.g., the amount oftime required for the image intensity of the left side of the patient'sheart to reach 50% (in one embodiment) or 25% (in another embodiment) ofthe image intensity of the right side of the patient's heart).

One or more prompts may be issued in relation to deriving a value forthe flow rate decay constant. Each such prompt may be issued at anyappropriate location and in any appropriate manner. Any appropriate dataentry vice may be utilized to input any appropriate value in relation toany such prompt, including without limitation a keyboard, a mouse, atouch screen display, a soft key display, a touch pad, a track ball, orthe like. Prompts may be issued in relation to a value for one or moreof an enhancement level variable, an acquisition time variable, and atime delay variable. A value for the flow rate decay constant may bederived for purposes of the fifth aspect in the manner discussed abovein relation to the third aspect.

A number of feature refinements and additional features are separatelyapplicable to each of the above-noted first through the fifth aspects ofthe present invention as well. These feature refinements and additionalfeatures may be used individually or in any combination in relation toeach of the first through the fifth aspects. Initially, any feature ofany other various aspects of the present invention that is intended tobe limited to a “singular” context or the like will be clearly set forthherein by terms such as “only,” “single,” “limited to,” or the like.Merely introducing a feature in accordance with commonly acceptedantecedent basis practice does not limit the corresponding feature tothe singular (e.g., indicating that the power injector includes “asyringe” alone does not mean that the power injector includes only asingle “syringe”). Moreover, any failure to use phrases such as “atleast one” also does not limit the corresponding feature to the singular(e.g., indicating that the power injector includes “a syringe” versus“at least one syringe” alone does not mean that the power injectorincludes only a single “syringe”). Finally, use of the phrase “at leastgenerally” or the like in relation to a particular feature encompassesthe corresponding characteristic and insubstantial variations thereof(e.g., indicating that a syringe barrel is at least generallycylindrical encompasses the syringe barrel being cylindrical; indicatingthat a maximum fluid volume is at least generally about 15 mLencompasses the maximum fluid volume being 15 mL).

Any “logic” that may be utilized by any of the various aspects of thepresent invention may be implemented in any appropriate manner,including without limitation in any appropriate software, firmware, orhardware, using one or more platforms, using one or more processors,using memory of any appropriate type, using any single computer of anyappropriate type or a multiple computers of any appropriate type andinterconnected in any appropriate manner, or any combination thereof.This logic may be implemented at any single location or at multiplelocations that are interconnected in any appropriate manner (e.g., viaany type of network).

The power injector may be of any appropriate size, shape, configuration,and/or type. The power injector may utilize one or more syringe plungerdrivers of any appropriate size, shape, configuration, and/or type,where each such syringe plunger driver is capable of at leastbi-directional movement (e.g., a movement in a first direction fordischarging fluid; a movement in a second direction for accommodating aloading of fluid or so as to return to a position for a subsequent fluiddischarge operation), and where each such syringe plunger driver mayinteract with its corresponding syringe plunger in any appropriatemanner (e.g., by mechanical contact; by an appropriate coupling(mechanical or otherwise)) so as to be able to advance the syringeplunger in at least one direction (e.g., to discharge fluid). Eachsyringe plunger driver may utilize one or more drive sources of anyappropriate size, shape, configuration, and/or type. Multiple drivesource outputs may be combined in any appropriate manner to advance asingle syringe plunger at a given time. One or more drive sources may bededicated to a single syringe plunger driver, one or more drive sourcesmay be associated with multiple syringe plunger drivers (e.g.,incorporating a transmission of sorts to change the output from onesyringe plunger to another syringe plunger), or a combination thereof.Representative drive source forms include a brushed or brushlesselectric motor, a hydraulic motor, a pneumatic motor, a piezoelectricmotor, or a stepper motor.

The power injector may be used for any appropriate application where thedelivery of one or more medical fluids is desired, including withoutlimitation any appropriate medical application (e.g., computedtomography or CT imaging; magnetic resonance imaging or MRI; singlephoton emission computed tomography or SPECT imaging; positron emissiontomography or PET imaging; X-ray imaging; angiographic imaging; opticalimaging; ultrasound imaging). The power injector may be used inconjunction with any component or combination of components, such as anappropriate imaging system (e.g., a CT scanner). For instance,information could be conveyed between any such power injector and one ormore other components (e.g., scan delay information, injection startsignal, injection rate).

Any appropriate number of syringes may be utilized with the powerinjector in any appropriate manner (e.g., detachably; front-loaded;rear-loaded; side-loaded), any appropriate medical fluid may bedischarged from a given syringe of any such power injector (e.g.,contrast media, a radiopharmaceutical, saline, and any combinationthereof), and any appropriate fluid may be discharged from a multiplesyringe power injector configuration in any appropriate manner (e.g.,sequentially, simultaneously), or any combination thereof. In oneembodiment, fluid discharged from a syringe by operation of the powerinjector is directed into a conduit (e.g., a medical tubing set), wherethis conduit is fluidly interconnected with the syringe in anyappropriate manner and directs fluid to a desired location (e.g., to acatheter that is inserted into a patient, for instance for injection).Multiple syringes may discharge into a common conduit (e.g., forprovision to a single injection site), or one syringe may discharge intoone conduit (e.g., for provision to one injection site), while anothersyringe may discharge into a different conduit (e.g., for provision to adifferent injection site). In one embodiment, each syringe includes asyringe barrel and a plunger that is disposed within and movablerelative to the syringe barrel. This plunger may interface with thepower injector's syringe plunger drive assembly such that the syringeplunger drive assembly is able to advance the plunger in at least onedirection, and possibly in two different, opposite directions.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic of one embodiment of a power injector.

FIG. 2A is a perspective view of one embodiment of a portablestand-mounted, dual-head power injector.

FIG. 2B is an enlarged, partially exploded, perspective view of apowerhead used by the power injector of FIG. 2A.

FIG. 2C is a schematic of one embodiment of a syringe plunger driveassembly used by the power injector of FIG. 2A.

FIG. 3 is a functional schematic of a CT scanner.

FIG. 4 is a functional schematic of one embodiment of an imaging system.

FIG. 5 is a functional schematic of one embodiment of power injectorcontrol logic that may be used by the power injector of the imagingsystem of FIG. 4.

FIG. 6 is one embodiment of a medical imaging protocol that may be usedby the power injector control logic of FIG. 5.

FIG. 7 is a functional schematic of another embodiment of power injectorcontrol logic that may be used by the power injector of the imagingsystem of FIG. 4.

FIG. 8 is one embodiment of a medical imaging protocol that may be usedby the power injector control logic of FIG. 7.

FIG. 9 is one embodiment of a test injection protocol that may be usedby the medical imaging protocol of FIG. 8.

DETAILED DESCRIPTION

FIG. 1 presents a schematic of one embodiment of a power injector 10having a powerhead 12. One or more graphical user interfaces or GUIs 11may be associated with the powerhead 12. Each GUI 11: 1) may be of anyappropriate size, shape, configuration, and/or type; 2) may beoperatively interconnected with the powerhead 12 in any appropriatemanner; 3) may be disposed at any appropriate location; 4) may beconfigured to provide one or any combination of the following functions:controlling one or more aspects of the operation of the power injector10; inputting/editing one or more parameters associated with theoperation of the power injector 10; and displaying appropriateinformation (e.g., associated with the operation of the power injector10); or 5) any combination of the foregoing. Any appropriate number ofGUIs 11 may be utilized. In one embodiment, the power injector 10includes a GUI 11 that is incorporated by a console that is separatefrom but which communicates with the powerhead 12. In anotherembodiment, the power injector 10 includes a GUI 11 that is part of thepowerhead 12. In yet another embodiment, the power injector 10 utilizesone GUI 11 on a separate console that communicates with the powerhead12, and also utilizes another GUI 11 that is on the powerhead 12. EachGUI 11 could provide the same functionality or set of functionalities,or the GUIs 11 may differ in at least some respect in relation to theirrespective functionalities.

A syringe 28 may be installed on this powerhead 12 and, when installed,may be considered to be part of the power injector 10. Some injectionprocedures may result in a relatively high pressure being generatedwithin the syringe 28. In this regard, it may be desirable to disposethe syringe 28 within a pressure jacket 26. The pressure jacket 26 istypically associated with the powerhead 12 in a manner that allows thesyringe 28 to be disposed therein as a part of or after installing thesyringe 28 on the powerhead 12. The same pressure jacket 26 willtypically remain associated with the powerhead 12, as various syringes28 are positioned within and removed from the pressure jacket 26 formultiple injection procedures. The power injector 10 may eliminate thepressure jacket 26 if the power injector 10 is configured/utilized forlow-pressure injections and/or if the syringe(s) 28 to be utilized withthe power injector 10 is (are) of sufficient durability to withstandhigh-pressure injections without the additional support provided by apressure jacket 26. In any case, fluid discharged from the syringe 28may be directed into a conduit 38 of any appropriate size, shape,configuration, and/or type, which may be fluidly interconnected with thesyringe 28 in any appropriate manner, and which may direct fluid to anyappropriate location (e.g., to a patient).

The powerhead 12 includes a syringe plunger drive assembly or syringeplunger driver 14 that interacts (e.g., interfaces) with the syringe 28(e.g., a plunger 32 thereof) to discharge fluid from the syringe 28.This syringe plunger drive assembly 14 includes a drive source 16 (e.g.,a motor of any appropriate size, shape, configuration, and/or type,optional gearing, and the like) that powers a drive output 18 (e.g., arotatable drive screw). A ram 20 may be advanced along an appropriatepath (e.g., axial) by the drive output 18. The ram 20 may include acoupler 22 for interacting or interfacing with a corresponding portionof the syringe 28 in a manner that will be discussed below.

The syringe 28 includes a plunger or piston 32 that is movably disposedwithin a syringe barrel 30 (e.g., for axial reciprocation along an axiscoinciding with the double-headed arrow B). The plunger 32 may include acoupler 34. This syringe plunger coupler 34 may interact or interfacewith the ram coupler 22 to allow the syringe plunger drive assembly 14to retract the syringe plunger 32 within the syringe barrel 30. Thesyringe plunger coupler 34 may be in the form of a shaft 36 a thatextends from a body of the syringe plunger 32, together with a head orbutton 36 b. However, the syringe plunger coupler 34 may be of anyappropriate size, shape, configuration, and/or type.

Generally, the syringe plunger drive assembly 14 of the power injector10 may interact with the syringe plunger 32 of the syringe 28 in anyappropriate manner (e.g., by mechanical contact; by an appropriatecoupling (mechanical or otherwise)) so as to be able to move or advancethe syringe plunger 32 (relative to the syringe barrel 30) in at leastone direction (e.g., to discharge fluid from the corresponding syringe28). That is, although the syringe plunger drive assembly 14 may becapable of bi-directional motion (e.g., via operation of the same drivesource 16), the power injector 10 may be configured such that theoperation of the syringe plunger drive assembly 14 actually only moveseach syringe plunger 32 being used by the power injector 10 in only onedirection. However, the syringe plunger drive assembly 14 may beconfigured to interact with each syringe plunger 32 being used by thepower injector 10 so as to be able to move each such syringe plunger 32in each of two different directions (e.g. in different directions alonga common axial path).

Retraction of the syringe plunger 32 may be utilized to accommodate aloading of fluid into the syringe barrel 30 for a subsequent injectionor discharge, may be utilized to actually draw fluid into the syringebarrel 30 for a subsequent injection or discharge, or for any otherappropriate purpose. Certain configurations may not require that thesyringe plunger drive assembly 14 be able to retract the syringe plunger32, in which case the ram coupler 22 and syringe plunger coupler 34 maynot be desired. In this case, the syringe plunger drive assembly 14 maybe retracted for purposes of executing another fluid delivery operation(e.g., after another pre-filled syringe 28 has been installed). Evenwhen a ram coupler 22 and syringe plunger coupler 34 are utilized, itmay such that these components may or may not be coupled when the ram 20advances the syringe plunger 32 to discharge fluid from the syringe 28(e.g., the ram 20 may simply “push on” the syringe plunger coupler 34 oron a proximal end of the syringe plunger 32). Any single motion orcombination of motions in any appropriate dimension or combination ofdimensions may be utilized to dispose the ram coupler 22 and syringeplunger coupler 34 in a coupled state or condition, to dispose the ramcoupler 22 and syringe plunger coupler 34 in an un-coupled state orcondition, or both.

The syringe 28 may be installed on the powerhead 12 in any appropriatemanner. For instance, the syringe 28 could be configured to be installeddirectly on the powerhead 12. In the illustrated embodiment, a housing24 is appropriately mounted on the powerhead 12 to provide an interfacebetween the syringe 28 and the powerhead 12. This housing 24 may be inthe form of an adapter to which one or more configurations of syringes28 may be installed, and where at least one configuration for a syringe28 could be installed directly on the powerhead 12 without using anysuch adapter. The housing 24 may also be in the form of a faceplate towhich one or more configurations of syringes 28 may be installed. Inthis case, it may be such that a faceplate is required to install asyringe 28 on the powerhead 12—the syringe 28 could not be installed onthe powerhead 12 without the faceplate. When a pressure jacket 26 isbeing used, it may be installed on the powerhead 12 in the variousmanners discussed herein in relation to the syringe 28, and the syringe28 will then thereafter be installed in the pressure jacket 26.

The housing 24 may be mounted on and remain in a fixed position relativeto the powerhead 12 when installing a syringe 28. Another option is tomovably interconnect the housing 24 and the powerhead 12 to accommodateinstalling a syringe 28. For instance, the housing 24 may move within aplane that contains the double-headed arrow A to provide one or more ofcoupled state or condition and an un-coupled state or condition betweenthe ram coupler 22 and the syringe plunger coupler 34.

One particular power injector configuration is illustrated in FIG. 2A,is identified by a reference numeral 40, and is at least generally inaccordance with the power injector 10 of FIG. 1. The power injector 40includes a powerhead 50 that is mounted on a portable stand 48. A pairof syringes 86 a, 86 b for the power injector 40 is mounted on thepowerhead 50. Fluid may be discharged from the syringes 86 a, 86 bduring operation of the power injector 40.

The portable stand 48 may be of any appropriate size, shape,configuration, and/or type. Wheels, rollers, casters, or the like may beutilized to make the stand 48 portable. The powerhead 50 could bemaintained in a fixed position relative to the portable stand 48.However, it may be desirable to allow the position of the powerhead 50to be adjustable relative to the portable stand 48 in at least somemanner. For instance, it may be desirable to have the powerhead 50 inone position relative to the portable stand 48 when loading fluid intoone or more of the syringes 86 a, 86 b, and to have the powerhead 50 ina different position relative to the portable stand 48 for performanceof an injection procedure. In this regard, the powerhead 50 may bemovably interconnected with the portable stand 48 in any appropriatemanner (e.g., such that the powerhead 50 may be pivoted through at leasta certain range of motion, and thereafter maintained in the desiredposition).

It should be appreciated that the powerhead 50 could be supported in anyappropriate manner for providing fluid. For instance, instead of beingmounted on a portable structure, the powerhead 50 could beinterconnected with a support assembly, that in turn is mounted to anappropriate structure (e.g., ceiling, wall, floor). Any support assemblyfor the powerhead 50 may be positionally adjustable in at least somerespect (e.g., by having one or more support sections that may berepositioned relative to one more other support sections), or may bemaintained in a fixed position. Moreover, the powerhead 50 may beintegrated with any such support assembly so as to either be maintainedin a fixed position or so as to be adjustable relative the supportassembly.

The powerhead 50 includes a graphical user interface or GUI 52. This GUI52 may be configured to provide one or any combination of the followingfunctions: controlling one or more aspects of the operation of the powerinjector 40; inputting/editing one or more parameters associated withthe operation of the power injector 40; and displaying appropriateinformation (e.g., associated with the operation of the power injector40). The power injector 40 may also include a console 42 and powerpack46 that each may be in communication with the powerhead 50 in anyappropriate manner (e.g., via one or more cables), that may be placed ona table or mounted on an electronics rack in an examination room or atany other appropriate location, or both. The powerpack 46 may includeone or more of the following and in any appropriate combination: a powersupply for the injector 40; interface circuitry for providingcommunication between the console 42 and powerhead 50; circuitry forpermitting connection of the power injector 40 to remote units such asremote consoles, remote hand or foot control switches, or other originalequipment manufacturer (OEM) remote control connections (e.g., to allowfor the operation of power injector 40 to be synchronized with the x-rayexposure of an imaging system); and any other appropriate componentry.The console 42 may include a touch screen display 44, which in turn mayprovide one or more of the following functions and in any appropriatecombination: allowing an operator to remotely control one or moreaspects of the operation of the power injector 40; allowing an operatorto enter/edit one or more parameters associated with the operation ofthe power injector 40; allowing an operator to specify and storeprograms for automated operation of the power injector 40 (which canlater be automatically executed by the power injector 40 upon initiationby the operator); and displaying any appropriate information relation tothe power injector 40 and including any aspect of its operation.

Various details regarding the integration of the syringes 86 a, 86 bwith the powerhead 50 are presented in FIG. 2B. Each of the syringes 86a, 86 b includes the same general components. The syringe 86 a includesplunger or piston 90 a that is movably disposed within a syringe barrel88 a. Movement of the plunger 90 a along an axis 100 a (FIG. 2A) viaoperation of the powerhead 50 will discharge fluid from within a syringebarrel 88 a through a nozzle 89 a of the syringe 86 a. An appropriateconduit (not shown) will typically be fluidly interconnected with thenozzle 89 a in any appropriate manner to direct fluid to a desiredlocation (e.g., a patient). Similarly, the syringe 86 b includes plungeror piston 90 b that is movably disposed within a syringe barrel 88 b.Movement of the plunger 90 b along an axis 100 b (FIG. 2A) via operationof the powerhead 50 will discharge fluid from within the syringe barrel88 b through a nozzle 89 b of the syringe 86 b. An appropriate conduit(not shown) will typically be fluidly interconnected with the nozzle 89b in any appropriate manner to direct fluid to a desired location (e.g.,a patient).

The syringe 86 a is interconnected with the powerhead 50 via anintermediate faceplate 102 a. This faceplate 102 a includes a cradle 104that supports at least part of the syringe barrel 88 a, and which mayprovide/accommodate any additional functionality or combination offunctionalities. A mounting 82 a is disposed on and is fixed relative tothe powerhead 50 for interfacing with the faceplate 102 a. A ram coupler76 of a ram 74 (FIG. 2C), which are each part of a syringe plunger driveassembly or syringe plunger driver 56 (FIG. 2C) for the syringe 86 a, ispositioned in proximity to the faceplate 102 a when mounted on thepowerhead 50. Details regarding the syringe plunger drive assembly 56will be discussed in more detail below in relation to FIG. 2C.Generally, the ram coupler 76 may be coupled with the syringe plunger 90a of the syringe 86 a, and the ram coupler 76 and ram 74 (FIG. 2C) maythen be moved relative to the powerhead 50 to move the syringe plunger90 a along the axis 100 a (FIG. 2A). It may be such that the ram coupler76 is engaged with, but not actually coupled to, the syringe plunger 90a when moving the syringe plunger 90 a to discharge fluid through thenozzle 89 a of the syringe 86 a.

The faceplate 102 a may be moved at least generally within a plane thatis orthogonal to the axes 100 a, 100 b (associated with movement of thesyringe plungers 90 a, 90 b, respectively, and illustrated in FIG. 2A),both to mount the faceplate 102 a on and remove the faceplate 102 a fromits mounting 82 a on the powerhead 50. The faceplate 102 a may be usedto couple the syringe plunger 90 a with its corresponding ram coupler 76on the powerhead 50. In this regard, the faceplate 102 a includes a pairof handles 106 a. Generally and with the syringe 86 a being initiallypositioned within the faceplate 102 a, the handles 106 a may be moved toin turn move/translate the syringe 86 a at least generally within aplane that is orthogonal to the axes 100 a, 100 b (associated withmovement of the syringe plungers 90 a, 90 b, respectively, andillustrated in FIG. 2A). Moving the handles 106 a to one positionmoves/translates the syringe 86 a (relative to the faceplate 102 a) inan at least generally downward direction to couple its syringe plunger90 a with its corresponding ram coupler 76. Moving the handles 106 a toanother position moves/translates the syringe 86 a (relative to thefaceplate 102 a) in an at least generally upward direction to uncoupleits syringe plunger 90 a from its corresponding ram coupler 76.

The syringe 86 b is interconnected with the powerhead 50 via anintermediate faceplate 102 b. A mounting 82 b is disposed on and isfixed relative to the powerhead 50 for interfacing with the faceplate102 b. A ram coupler 76 of a ram 74 (FIG. 2C), which are each part of asyringe plunger drive assembly 56 for the syringe 86 b, is positioned inproximity to the faceplate 102 b when mounted to the powerhead 50.Details regarding the syringe plunger drive assembly 56 again will bediscussed in more detail below in relation to FIG. 2C. Generally, theram coupler 76 may be coupled with the syringe plunger 90 b of thesyringe 86 b, and the ram coupler 76 and ram 74 (FIG. 2C) may be movedrelative to the powerhead 50 to move the syringe plunger 90 b along theaxis 100 b (FIG. 2A). It may be such that the ram coupler 76 is engagedwith, but not actually coupled to, the syringe plunger 90 b when movingthe syringe plunger 90 b to discharge fluid through the nozzle 89 b ofthe syringe 86 b.

The faceplate 102 b may be moved at least generally within a plane thatis orthogonal to the axes 100 a, 100 b (associated with movement of thesyringe plungers 90 a, 90 b, respectively, and illustrated in FIG. 2A),both to mount the faceplate 102 b on and remove the faceplate 102 b fromits mounting 82 b on the powerhead 50. The faceplate 102 b also may beused to couple the syringe plunger 90 b with its corresponding ramcoupler 76 on the powerhead 50. In this regard, the faceplate 102 b mayinclude a handle 106 b. Generally and with the syringe 86 b beinginitially positioned within the faceplate 102 b, the syringe 86 b may berotated along its long axis 100 b (FIG. 2A) and relative to thefaceplate 102 b. This rotation may be realized by moving the handle 106b, by grasping and turning the syringe 86 b, or both. In any case, thisrotation moves/translates both the syringe 86 b and the faceplate 102 bat least generally within a plane that is orthogonal to the axes 100 a,100 b (associated with movement of the syringe plungers 90 a, 90 b,respectively, and illustrated in FIG. 2A). Rotating the syringe 8613 inone direction moves/translates the syringe 86 b and faceplate 102 b inan at least generally downward direction to couple the syringe plunger90 b with its corresponding ram coupler 76. Rotating the syringe 86 b inthe opposite direction moves/translates the syringe 86 b and faceplate102 b in an at least generally upward direction to uncouple its syringeplunger 90 b from its corresponding ram coupler 76.

As illustrated in FIG. 2B, the syringe plunger 90 b includes a plungerbody 92 and a syringe plunger coupler 94. This syringe plunger coupler94 includes a shaft 98 that extends from the plunger body 92, along witha head 96 that is spaced from the plunger body 92. Each of the ramcouplers 76 includes a larger slot that is positioned behind a smallerslot on the face of the ram coupler 76. The head 96 of the syringeplunger coupler 94 may be positioned within the larger slot of the ramcoupler 76, and the shaft 98 of the syringe plunger coupler 94 mayextend through the smaller slot on the face of the ram coupler 76 whenthe syringe plunger 90 b and its corresponding ram coupler 76 are in acoupled state or condition. The syringe plunger 90 a may include asimilar syringe plunger coupler 94 for interfacing with itscorresponding ram coupler 76.

The powerhead 50 is utilized to discharge fluid from the syringes 86 a,86 b in the case of the power injector 40. That is, the powerhead 50provides the motive force to discharge fluid from each of the syringes86 a, 86 b. One embodiment of what may be characterized as a syringeplunger drive assembly or syringe plunger driver is illustrated in FIG.2C, is identified by reference numeral 56, and may be utilized by thepowerhead 50 to discharge fluid from each of the syringes 86 a, 86 b. Aseparate syringe plunger drive assembly 56 may be incorporated into thepowerhead 50 for each of the syringes 86 a, 86 b. In this regard andreferring back to FIGS. 2A-B, the powerhead 50 may include hand-operatedknobs 80 a and 80 b for use in separately controlling each of thesyringe plunger drive assemblies 56.

Initially and in relation to the syringe plunger drive assembly 56 ofFIG. 2C, each of its individual components may be of any appropriatesize, shape, configuration and/or type. The syringe plunger driveassembly 56 includes a motor 58, which has an output shaft 60. A drivegear 62 is mounted on and rotates with the output shaft 60 of the motor58. The drive gear 62 is engaged or is at least engageable with a drivengear 64. This driven gear 64 is mounted on and rotates with a drivescrew or shaft 66. The axis about which the drive screw 66 rotates isidentified by reference numeral 68. One or more bearings 72appropriately support the drive screw 66.

A carriage or ram 74 is movably mounted on the drive screw 66.Generally, rotation of the drive screw 66 in one direction axiallyadvances the ram 74 along the drive screw 66 (and thereby along axis 68)in the direction of the corresponding syringe 86 a/b, while rotation ofthe drive screw 66 in the opposite direction axially advances the ram 74along the drive screw 66 (and thereby along axis 68) away from thecorresponding syringe 86 a/b. In this regard, the perimeter of at leastpart of the drive screw 66 includes helical threads 70 that interfacewith at least part of the ram 74. The ram 74 is also movably mountedwithin an appropriate bushing 78 that does not allow the ram 74 torotate during a rotation of the drive screw 66. Therefore, the rotationof the drive screw 66 provides for an axial movement of the ram 74 in adirection determined by the rotational direction of the drive screw 66.

The ram 74 includes a coupler 76 that that may be detachably coupledwith a syringe plunger coupler 94 of the syringe plunger 90 a/b of thecorresponding syringe 86 a/b. When the ram coupler 76 and syringeplunger coupler 94 are appropriately coupled, the syringe plunger 90 a/bmoves along with ram 74. FIG. 2C illustrates a configuration where thesyringe 86 a/b may be moved along its corresponding axis 100 a/b withoutbeing coupled to the ram 74. When the syringe 86 a/b is moved along itscorresponding axis 100 a/b such that the head 96 of its syringe plunger90 a/b is aligned with the ram coupler 76, but with the axes 68 still inthe offset configuration of FIG. 2C, the syringe 86 a/b may betranslated within a plane that is orthogonal to the axis 68 along whichthe ram 74 moves. This establishes a coupled engagement between the ramcoupler 76 and the syringe plunger coupler 96 in the above-noted manner.

The power injectors 10, 40 of FIGS. 1 and 2A-C each may be used for anyappropriate application, including without limitation for medicalimaging applications where fluid is injected into a subject (e.g., apatient). Representative medical imaging applications for the powerinjectors 10, 40 include without limitation computed tomography or CTimaging, magnetic resonance imaging or MRI, single photon emissioncomputed tomography or SPECT imaging, positron emission tomography orPET imaging, X-ray imaging, angiographic imaging, optical imaging, andultrasound imaging. The power injectors 10, 40 each could be used aloneor in combination with one or more other components. The power injectors10, 40 each may be operatively interconnected with one or morecomponents, for instance so that information may be conveyed between thepower injector 10, 40 and one or more other components (e.g., scan delayinformation, injection start signal, injection rate).

Any number of syringes may be utilized by each of the power injectors10, 40, including without limitation single-head configurations (for asingle syringe) and dual-head configurations (for two syringes). In thecase of a multiple syringe configuration, each power injector 10, 40 maydischarge fluid from the various syringes in any appropriate manner andaccording to any timing sequence (e.g., sequential discharges from twoor more syringes, simultaneous discharges from two or more syringes, orany combination thereof). Multiple syringes may discharge into a commonconduit (e.g., for provision to a single injection site), or one syringemay discharge into one conduit (e.g., for provision to one injectionsite), while another syringe may discharge into a different conduit(e.g., for provision to a different injection site). Each such syringeutilized by each of the power injectors 10, 40 may include anyappropriate fluid (e.g., a medical fluid), for instance contrast media,a radiopharmaceutical, saline, and any combination thereof. Each suchsyringe utilized by each of the power injectors 10, 40 may be installedin any appropriate manner (e.g., rear-loading configurations may beutilized; front-loading configurations may be utilized; side-loadingconfigurations may be utilized).

FIG. 3 illustrates a functional schematic of a computed tomography or CTscanner 110. The CT scanner 110 includes an X-ray tube 112 that emits anX-ray beam 114. The X-ray beam 114 is gated by a beam diaphragm 116,proceeds through a patient 140, and is incident on a radiation detector118. The X-rays incident on the radiation detector 118 are attenuated bythe patient 140. The radiation detector 118 generates electrical signalscorresponding to the attenuated X-ray incident thereon.

The X-ray tube 112 and the radiation detector 118 are mounted on agantry 120 which may be rotated by a drive 122. The X-ray beam 114 istherefore caused to rotate around the patient 140, so that a series ofprojections are made, each being typically obtained at a differentprojection angle. Each projection has a dataset of the aforementionedelectrical signals associated therewith. The dataset from eachprojection is supplied from the radiation detector 118 to a datameasurement system 124 for collection and editing. Moreover, thesedatasets are supplied from the data measurement system 124 to an imagereconstruction computer 126, which in turn constructs a CT image of thepatient 140 from the projection data in a known manner. This image isdisplayed on a monitor 128 connected to the image reconstructioncomputer 126.

The CT scanner 110 also includes a user interface 130 that is connectedto the image reconstruction computer 126. The image reconstructioncomputer 126 may also serve as an overall system control computer andthereby may include connections in a known manner (not shown) to variouscomponents, such as the drive 122, a voltage supply for the X-ray tube112 and that is embodied in a tube current controller 132, and the beamdiaphragm 116. Alternatively, a separate control computer can be usedfor these purposes.

The CT scanner 110 may also include an exposure controller 134 and adose monitor 136. The exposure controller 134 receives a signal from thedose monitor 136, which is disposed in the X-ray beam 114, indicatingthe intensity of the X-rays before being attenuated by the patient 140.The exposure controller 134 also receives signals from the datameasurement system 124, representing the attenuated X-rays, so that theexposure controller 134 can calculate an attenuation profile of thepatient 140 from the signals from the dose monitor 136 and the datameasurement system 124.

One embodiment of an imaging system is illustrated in FIG. 4 and isidentified by reference numeral 150. The imaging system 150 includes animaging unit 152 and a power injector 154. The imaging unit 152 may beof any appropriate size, shape, configuration, and/or type, and itsimage-acquisition functionality may utilize any appropriate technologyor combination of technologies. In one embodiment, the imaging unit 152is in the form of a computed tomography scanner, for instance the CTscanner 110 shown in FIG. 3.

The power injector 154 of the imaging system 150 also may be of anyappropriate size, shape, configuration, and/or type, for instance in theform of the power injectors 10, 40 discussed above. In any case, thepower injector 154 is fluidly interconnected with a patient 156 in anyappropriate manner (e.g., via an appropriate tubing set). One or morefluids may be injected into the patient 156 for purposes of acquiring animage of the patient 156 (e.g., a “patient image”) through operation ofthe imaging unit 152. Any appropriate patient image may be acquired bythe imaging system 150. In one embodiment, the patient image is in theform of a computed tomography angiogram or CTA—an image of the heart ofthe patient.

The power injector 154 from the imaging system 150 of FIG. 4 may utilizepower injector control logic to control one or more aspects of itsoperation. One representative embodiment of such power injector controllogic is illustrated in FIG. 5 and is identified by reference numeral160. The power injector control logic 160 may be configured to includeone or more injection protocols 162 and a decay constant cross-reference164. Each injection protocol 162 may utilize one or more fluids of anyappropriate type (e.g., contrast media, saline), may include one or morephases, or both. Each phase may be defined as a delivery (e.g., forinjection) of a predefined quantity of a predefined fluid in apredefined manner (e.g., one or more fixed flow rates, one or morevariable flow rates, or a combination thereof). One or more of theinjection protocols 162 may provide an exponentially decaying flow rateinjection that is intended to optimize usage of contrast media, toprovide a desired level/manner of enhancement of a region of interest ofthe patient 156 to be imaged, or both. Any appropriate number of theinjection protocols 162 of the power injector control logic 160 mayprovide an exponentially decaying flow rate injection (e.g., not all ofthe injection protocols 162 of the power injector control logic 160 needto be configured to provide an exponentially decaying flow rateinjection, although such could be the case). In one embodiment, at leastone injection protocol 162 provides an exponentially decaying flow rateinjection, while at least one injection protocol 162 does not providesuch an exponentially decaying flow rate injection.

The decay constant cross-reference 164 of the power injector controllogic 160 may store flow rate decay constant information (to provide theabove-noted exponentially decaying flow rate injection) on an imagingunit 152 model or model number basis. The decay constant cross-reference164 may be of any appropriate configuration to associate a particularmodel or model number of an imaging unit 152 with a particular flow ratedecay constant. The flow rate decay constant for a particular model ofimaging unit 152 may be determined or established in any appropriatemanner (e.g., empirically). Any number of imaging unit 152 model/flowrate decay constant pairs may be stored in the decay constantcross-reference 164. Data for the decay constant cross-reference 164 maybe stored in any appropriate manner (e.g., any appropriate datastructure or data storage technique may be utilized for purposes of thedecay constant cross-reference 164).

Different models of imaging units 152 may benefit in at least somerespect from executing an injection protocol 162 using different flowrate decay constants. Any appropriate way may be utilized by a powerinjector 154 (that incorporates the power injector control logic 160 ofFIG. 5) in relation to retrieving a flow rate decay constant for aparticular model of imaging unit 152 from the decay constantcross-reference 164. In one embodiment, the decay constantcross-reference 164 may be searched by entering a model, model number,or some other identifier for an imaging unit 152 that is to be used toacquire a patient image. In another embodiment, the power injector 154includes a decay constant cross-reference 164 in the form of a drop-downmenu or the like that lists a plurality of model or model numbers ofimaging units 152, along with their associated flow rate decay constant.A user may then simply scroll through this drop-down menu.

One embodiment of a medical imaging protocol is illustrated in FIG. 6,is identified by reference numeral 170, and may be utilized by the powerinjector control logic 160 of FIG. 5. FIG. 6 will be described for thecase of the power injector control logic 160 being used by the powerinjector 154 from the imaging system 150 of FIG. 4. The medical imagingprotocol 170 includes identifying a model or model number of an imagingunit 152 (FIG. 4) that is to be used to acquire a patient image inaccordance with step 172. A search is undertaken via step 174 toidentify a flow rate decay constant from the model or model numberinformation provided through execution of step 172. Step 174 may utilizethe decay constant cross-reference 164 from the power injector controllogic 160 of FIG. 5. However, any appropriate search may be utilized forpurposes of step 174, for instance using the Internet and an appropriatesearch engine (e.g., inputting a model number of an imaging unit 152 inan appropriate search engine to identify an associated flow rate decayconstant).

A flow rate decay constant, identified from the search of step 174, maybe input to the power injector 154 (FIG. 4) through execution of step176 of the medical imaging protocol 170 of FIG. 6. This flow rate decayconstant may be input to the power injector 154 in any appropriatemanner, for instance through a setup screen of the power injector 154(FIG. 4) using any appropriate data entry device or any combination ofdata entry devices. In any case and in accordance with step 178 of themedical imaging protocol 170, an injection protocol 162 is executedusing this input flow rate decay constant. The imaging unit 152 (FIG. 4)may be operated to acquire a patient image pursuant to step 180 (e.g.,for a computed tomography angiogram). The imaging unit 152 may acquireone or more patient images using the injection protocol 162 from step178. The imaging unit 152 could also acquire one or more additionalpatient images using one or more other injection protocols 162 (otherthan the protocol 162 associated with step 178).

Another embodiment of power injector control logic is illustrated inFIG. 7, is identified by reference numeral 190, and may be utilized bythe power injector 154 from the imaging system 150 of FIG. 4. The powerinjector control logic 190 includes one or more of the above-notedinjection protocols 162 in the same manner as the power injector controllogic 160 of FIG. 5. Another component or functionality of the powerinjector control logic 190 of FIG. 7 is a decay constant determinationprotocol or logic 192. This decay constant determination logic 192 mayutilize data acquired through execution of a test injection protocol194, that may also part of the power injector control logic 190. In oneembodiment, the decay constant determination logic 192 uses dataacquired from execution of a test injection protocol 194 to derive orcalculate a flow rate decay constant to be used by an injection protocol162 to facilitate acquisition of a patient image (e.g., using theimaging system 150 of FIG. 4).

A functional schematic of one embodiment of a medical imaging protocol200 is illustrated in FIG. 8, and may be used by the imaging system 150of FIG. 4 when incorporating the power injector control logic 190 ofFIG. 7. The medical imaging protocol 200 includes injecting a firstfluid into a patient 156 (FIG. 4) through execution of step 202. In oneembodiment, this first fluid is contrast media. Step 202 may be referredto as a “first injection.” This first injection may utilize anyappropriate fluid or combination of fluids (e.g., contrast media, aloneor in combination with saline), may inject any appropriate fluid volume(e.g., no more than at least generally about 15 mL in one embodiment; nomore than at least generally about 10 mL in one embodiment; within arange at least generally from about 5 mL to at least generally about 15mL (inclusive) in one embodiment), and may utilize any appropriate flowrate (e.g., a constant flow rate within a range of at least generallyabout 3-6 mL/second in one embodiment; a constant flow rate within arange of at least generally about 4-5 mL/second in one embodiment; aconstant flow rate of no more than at least generally about 6 mL/secondin one embodiment).

The above-noted first injection associated with step 202 of the protocol200 may be monitored in at least some manner pursuant to step 204. Aflow rate decay constant is derived from the first injection (step 202)in accordance with step 206, for instance using data acquired from thefirst injection through execution of step 204. Although the powerinjector 154 (FIG. 4) could be used for this derivation, any appropriateway of executing the derivation may be used for step 206 (e.g., ahand-calculation, where the result(s) are subsequently manually input tothe power injector 154). An injection protocol 162 is then executed bythe power injector 154 (FIG. 4) pursuant to step 208 and using the flowrate decay constant from step 206. A patient image is acquired throughexecution of step 210. In one embodiment, the patient image of step 210is for purposes of a computed tomography angiogram of a heart. As in thecase of the medical imaging protocol 170 of FIG. 6, one or more patientimages may also be acquired using one or more injection protocols 162other than that associated with step 208.

One embodiment of a test injection protocol for a heart imagingapplication (e.g., a computed tomography angiogram) is identified byreference numeral 220, is illustrated in FIG. 9, and may be used as thetest injection protocol 194 for the power injector control logic 190 ofFIG. 7. In one embodiment, the test injection protocol 220 may be usedfor purposes of steps 202, 204, and 206 of the medical imaging protocol200 of FIG. 8. In any case, steps 222 and 224 of the test injectionprotocol 220 are data input steps, and may be executed in any order andin any appropriate manner. Step 222 is directed to inputting a value foran acquisition time variable. Any appropriate value may be used as theacquisition time variable for purposes of step 222. For instance, anoperator may input a value for the acquisition time variable of step 222based upon prior knowledge, for instance what has been determined to bean average acquisition time over imaging multiple patients 156 using theimaging unit 152 (FIG. 4) or a “norm.” In one embodiment, it may beknown that about five seconds is required to acquire a suitable image ofthe heart (e.g., about 5 heartbeats) using a particular imaging unit152. Alternatively, the value for the acquisition time variable for step222 of the medical imaging protocol 220 may be specific to the patient156 that is to be imaged. With regard to this patient-specific option,the number of heartbeats required for the imaging unit 152 to acquire asuitable image of the heart of the patient 156 (e.g., an empiricallyknown value) may be divided by the number of heartbeats of the patient156 per unit of time (e.g., heartbeats per minute) to acquire a valuefor the acquisition time variable for step 222.

Step 224 of the test injection protocol 220 is directed to inputting avalue for an enhancement level variable. The value for the enhancementlevel variable for step 224 may be expressed as a percentage, forinstance a desired level of enhancement for the left side of the heartof the patient 156 in relation to the right side of the heart of thepatient 156. A 50% value for the enhancement level variable of step 224would be equated with the target enhancement level for the left side ofthe heart of the patient 156 being 50% of the enhancement level of theright side of the heart of the patient 156 during an imaging procedure(e.g., enhancement via a contrast media injection) for purposes of thetest injection protocol 220. The enhancement level variable for step 224may be at least generally about 50% in one embodiment, and may be atleast generally about 25% in another embodiment.

The test injection protocol 220 of FIG. 9 uses the first fluid injectionstep 202 discussed above in relation to the medical imaging protocol 200of FIG. 8. Step 226 of the test injection protocol 220 is directed tomonitoring a patient image to determine the time required to reach theenhancement level input in step 224. This time for purposes of step 226may be referred to as a “time delay” or “time delay variable.” Any wayof monitoring may be utilized for purposes of step 226. For instance,this monitoring step 226 may utilize obtaining an intensity measurementof the left side of the heart of the patient 156, as well as obtainingan intensity measurement of the right side of the heart of the patient.The time for purposes of step 226 would be the time that has elapsedfrom the start of the first fluid injection of step 202, until reachingthe input enhancement level from step 224 on the left side of the heartof the patient 156.

A flow rate decay constant may be derived or calculated from dataassociated with steps 222, 224, and 226. In one embodiment the flow ratedecay constant may be determined by the following equation:

$D_{c} = \frac{{LN}\; {EL}}{{TD} - {0.5({AT})}}$

where “LN” is the natural logarithm, where EL is the input value for theenhancement level variable from step 224, where TD is the timedetermined in accordance with step 226, and where AT is the value forthe acquisition time variable input in step 222. Step 228 is directed tocalculating the numerator for the above-noted equation, step 230 isdirected to calculating the denominator for the above-noted equation,and step 232 is directed to dividing the numerator (step 228) by thedenominator (step 230) to determine the flow rate decay constant.

Each of the power injector control logic 160 (FIG. 5) and the powerinjector control logic 190 (FIG. 7) may be implemented in anyappropriate manner, including without limitation in any appropriatesoftware, firmware, or hardware, using one or more platforms, using oneor more processors, using memory of any appropriate type, using anysingle computer of any appropriate type or a multiple computers of anyappropriate type and interconnected in any appropriate manner, or anycombination thereof. Each of the power injector control logic 160 (FIG.5) and the power injector control logic 190 (FIG. 7) may be implementedat any single location or at multiple locations that are interconnectedin any appropriate manner (e.g., via any type of network).

The foregoing description of the present invention has been presentedfor purposes of illustration and description. Furthermore, thedescription is not intended to limit the invention to the form disclosedherein. Consequently, variations and modifications commensurate with theabove teachings, and skill and knowledge of the relevant art, are withinthe scope of the present invention. The embodiments describedhereinabove are further intended to explain best modes known ofpracticing the invention and to enable others skilled in the art toutilize the invention in such, or other embodiments and with variousmodifications required by the particular application(s) or use(s) of thepresent invention. It is intended that the appended claims be construedto include alternative embodiments to the extent permitted by the priorart.

1. A power injector comprising: a syringe plunger driver comprising a motorized drive source; a syringe comprising a syringe plunger, wherein said syringe plunger driver interacts with said syringe plunger to move said syringe plunger within said syringe in at least a first direction; power injector control logic comprising an injection protocol that in turn comprises a flow rate decay constant; and data storage accessible by said power injector control logic and comprising a plurality of data entries, wherein each said data entry comprises a different flow rate decay constant value.
 2. (canceled)
 3. The power injector of claim 1, further comprising a graphical user interface.
 4. The power injector of claim 3, further comprising a first output on said graphical user interface, wherein said first output comprises a listing of at least some of said plurality of data entries and an associated said flow rate decay constant value.
 5. The power injector of claim 1, wherein said power injector is configured to accommodate searching of said data storage.
 6. The power injector of claim 1, further comprising a data input device operatively interconnected with said power injector control logic, wherein a selected one of a flow rate decay constant value may be input to said injection protocol through said data input device.
 7. A power injector comprising: a syringe plunger driver comprising a motorized drive source; a syringe comprising a syringe plunger, wherein said syringe plunger driver interacts with said syringe plunger to move said syringe plunger within said syringe in at least a first direction; power injector control logic comprising an injection protocol that in turn comprises a decay constant, wherein said power injector control logic further comprises decay constant determination logic.
 8. The power injector of claim 7, wherein said decay constant determination logic comprises a test injection protocol.
 9. The power injector of claim 7, wherein said decay constant determination logic comprises an acquisition time variable.
 10. The power injector of claim 9, further comprising a prompt for inputting a value for said acquisition time variable.
 11. The power injector of claim 9, further comprising an average value input for said acquisition time variable.
 12. The power injector of claim 9, further comprising a patient-specific value input for said acquisition time variable.
 13. The power injector of claim 7, wherein said decay constant determination logic comprises an enhancement level variable.
 14. The power injector of claim 13, further comprising a prompt for inputting a value for said enhancement level variable.
 15. The power injector of claim 7, wherein said decay constant determination logic comprises a time delay variable.
 16. The power injector of claim 15, wherein a value for said time delay variable is patient specific.
 17. The power injector of claim 15, further comprising a prompt for inputting a value for said time delay variable.
 18. The power injector of claim 7, wherein said decay constant determination logic comprises an acquisition time variable, an enhancement level variable, and a time delay variable, wherein a decay constant value provided by said decay constant determination logic is equal to a natural logarithm of said enhancement level variable, divided by a first value, wherein said first value is said time delay variable, minus ½ of said acquisition time variable.
 19. An imaging system comprising an imaging unit and the power injector of claim 18, wherein said acquisition time variable is a number of heartbeats required for said imaging unit to acquire a first patient heart image, divided by a number of patient heartbeats per unit of time, wherein said enhancement level variable is an expressed percentage of an intensity of a right side of a patients heart that is required for a left side of a patients heart to reach before acquiring the first patient heart image, and wherein said time delay variable is a time required to realize a value for said enhancement level variable during execution of a test injection protocol.
 20. A method for acquiring a medical image with an imaging system comprising a power injector and an imaging unit, said method comprising: searching for a first value for a flow rate decay constant based upon a model of said imaging unit; inputting said first value to said power injector; and delivering an injection with said power injector and using said first value.
 21. The method of claim 20, further comprising prompting an entry of a value for flow rate decay constant.
 22. The method of claim 21, wherein said prompting step is executed on a display associated with said power injector.
 23. The method of claim 20, wherein said searching step comprises accessing a cross-reference of imaging unit model numbers to flow rate decay constants.
 24. The method of claim 20, wherein said searching step comprises retrieving said first value from memory utilized by said power injector.
 25. The method of claim 20, wherein said searching step comprises accessing a lookup table incorporated by said power injector.
 26. The method of claim 20, wherein said searching step comprising using the Internet.
 27. The method of claim 20, further comprising the step of acquiring a medical image by operation of said imaging unit.
 28. A method for acquiring a medical image with an imaging system comprising a power injector and an imaging unit, said method comprising: delivering a first injection into a patient; monitoring said first injection; deriving a flow rate decay constant from said monitoring step; and delivering a second injection into said patient, wherein said second injection comprises using said flow rate decay constant.
 29. The method of claim 28, wherein said first injection comprises a test injection.
 30. The method of claim 28, wherein said first injection comprises injecting a fluid volume of no more than about 15 mL.
 31. The method of claim 28, wherein said first injection comprises using contrast media.
 32. The method of claim 28, wherein said monitoring step comprises acquiring data on said first injection.
 33. The method of claim 28, wherein said monitoring step comprises acquiring patient-specific data.
 34. The method of claim 28, wherein said monitoring step comprises monitoring an image intensity of a heart of said patient.
 35. The method of claim 34, wherein said deriving step comprises selecting a time delay value from said monitoring step, wherein said time delay value comprises an amount of time required after initiating said first injection for an image intensity of a left side of said heart to reach a predetermined level.
 36. The method of claim 35, wherein said predetermined level is expressed as a percentage of an image intensity of a right side of said heart.
 37. The method of claim 35, further comprising inputting said predetermined level to said power injector.
 38. The method of claim 35, wherein said deriving step comprises prompting entry of a value for said predetermined level.
 39. The method of claim 35, wherein said predetermined level is within about 25% of an image intensity of a right side of said heart.
 40. The method of claim 35, further comprising prompting entry of a value for an acquisition time variable, wherein said acquisition time variable is a number of heartbeats required for said imaging unit to acquire a first patient heart image, divided by a number of patient heartbeats per unit of time, wherein said deriving step comprises using said acquisition time variable.
 41. The method of claim 35, further comprising prompting entry of a time delay variable, wherein said time delay variable is a time required to realize said enhancement level variable provided by said first injection, wherein said deriving step comprises using said time delay variable.
 42. The method of claim 35, wherein said deriving step comprises using an acquisition time variable and a time delay variable, wherein deriving step comprises taking a natural logarithm of said enhancement level variable, divided by a first value, wherein said first value is said time delay variable, minus ½ of said acquisition time variable.
 43. The method of claim 28, wherein said deriving step comprises using an acquisition time variable, an enhancement level variable, and a time delay factor, wherein said deriving step comprises taking a natural logarithm of said enhancement level variable, divided by a first value, wherein said first value is said time delay variable, minus ½ of said acquisition time variable, wherein said acquisition time variable is a number of heartbeats required for said imaging unit to acquire a first patient heart image, divided by a number of patient heartbeats per unit of time, wherein said enhancement level variable is an expressed percentage of an intensity of a right side of a patient's heart that is required for a left side of a patient's heart to reach before acquiring the first patient heart image, and wherein said time delay variable is a time required to realize a value for said enhancement level factor during execution of a test injection protocol.
 44. A power injector comprising: a syringe plunger driver comprising a motorized drive source; a syringe comprising a syringe plunger, wherein said syringe plunger driver interacts with said syringe plunger to move said syringe plunger within said syringe in at least a first direction; power injector control logic comprising an injection protocol that in turn comprises a flow rate decay constant; and data storage accessible by said power injector control logic and comprising a plurality of data entries, wherein each said data entry comprises a flow rate decay constant value associated with an imaging device identifier.
 45. The power injector of claim 44, further comprising a graphical user interface.
 46. The power injector of claim 45, further comprising a first output on said graphical user interface, wherein said first output comprises a listing of at least some of said plurality of data entries and an associated said flow rate decay constant value.
 47. The power injector of claim 44, wherein said power injector is configured to accommodate searching of said data storage.
 48. The power injector of claim 44, further comprising a data input device operatively interconnected with said power injector control logic, wherein a selected one of a flow rate decay constant value may be input to said injection protocol through said data input device. 